A Process-Adaptive Cell-Based Cyclic Time-to-Digital Converter Using One-Way Varactor Cells

Abstract

Time-to-digital converters (TDCs) are commonly used for on-chip instrumentation. This article proposes a low-cost Cyclic-TDC with several distinct features. It can adapt to the process variation to maintain a fine resolution across all process corners. This is made possible by a so-called one-way varactor cell (OWVC) and an autonomous calibration process. In addition, it supports easy process migration. Last but not least, we show how it can be used for clock jitter measurement with reduced output uncertainty. Simulation results using a 90-nm CMOS process and a 40-nm CMOS process are used to demonstrate their advantages.